Anger by its very nature is illogical. People get angry because something appeals to it other than logic. Its something that they do not understand or its something that triggers a primal instinct to fight. Extreme emotions ,extreme love, extreme hurt, extreme feeling of betrayal or even an extreme form of happiness sets off anger. Anger is neither good or bad. Its neither harmful nor useful. The actions resulting from the anger results in destructiveness or constructivity. Without emanating actions , anger is like a detonator without the explosive. The quality of explosive determines the quality of explosion , rather than that of the detonator.
Trying to justify anger is like justifying hunger or sleep. There is no justification . It happens precisely because there IS no justification,no logic or background casuality. Trying to control anger is not possible . If its possible its just that you are not angry enough yet,or maybe your threshold of breakdown hasnt come yet. Neither is "chanellising" anger possible. Actions arising from anger may be put in a certain format to define "good" or "bad". It is important that we try not to "understand" or "label" anger. Like most emotions , love, hatred or pain..anger will defy logic or explanations. Any explanations would lead to a lot of wild goose chases which will confuse ordinary human beings and lead to tangential thoughtlines.